ct said 16 gb ram full and host said 6,7 gb ram used?

Hi,

we have a question. our host said ram in use are 6.7 gb of 64 gb and a ct on his host has 15.8 gb of 16 gb in use. why a ct have more ram in use as a host have in use? is the ram usage of host not the sum of ram usage of all ct´s and vm´s complete?

regards